Key Verses

1. 9:77At-Tawbah
   فَأَعۡقَبَهُمۡ نِفَاقٗا فِي قُلُوبِهِمۡ إِلَىٰ يَوۡمِ يَلۡقَوۡنَهُۥ بِمَآ أَخۡلَفُواْ ٱللَّهَ مَا وَعَدُوهُ وَبِمَا كَانُواْ يَكۡذِبُونَ
   So He hath made the consequence (to be) hypocrisy in their hearts until the day when they shall meet Him, because they broke their word to Allah that they promised Him, and because they lied.
   In context

   Allah therefore firmly established hypocrisy in their hearts until the Day of Judgement, as a punishment for their breaking their promise with Allah and for their lying.

2. 9:97At-TawbahWarning
   ٱلۡأَعۡرَابُ أَشَدُّ كُفۡرٗا وَنِفَاقٗا وَأَجۡدَرُ أَلَّا يَعۡلَمُواْ حُدُودَ مَآ أَنزَلَ ٱللَّهُ عَلَىٰ رَسُولِهِۦۗ وَٱللَّهُ عَلِيمٌ حَكِيمٞ
   The wandering Arabs are more hard in disbelief and hypocrisy, and more likely to be ignorant of the limits which Allah hath revealed unto His messenger. And Allah is Knower, Wise.
   In context

   If the people of the desert are of those who adopt disbelief or hypocrisy, then their disbelief and hypocrisy is stronger than that of others who live in city areas. They are also more likely to be ignorant of religion and the obligatory and recommended acts of the sacred law that Allah has revealed to His Messenger.

3. 9:101At-TawbahWarning
   وَمِمَّنۡ حَوۡلَكُم مِّنَ ٱلۡأَعۡرَابِ مُنَٰفِقُونَۖ وَمِنۡ أَهۡلِ ٱلۡمَدِينَةِ مَرَدُواْ عَلَى ٱلنِّفَاقِ لَا تَعۡلَمُهُمۡۖ نَحۡنُ نَعۡلَمُهُمۡۚ سَنُعَذِّبُهُم مَّرَّتَيۡنِ ثُمَّ يُرَدُّونَ إِلَىٰ عَذَابٍ عَظِيمٖ
   And among those around you of the wandering Arabs there are hypocrites, and among the townspeople of Al-Madinah (there are some who) persist in hypocrisy whom thou (O Muhammad) knowest not. We, We know them, and We shall chastise them twice; then they will be relegated to a painful doom.
   In context

   Some of those who live in the desert surrounding Medina are hypocrites, as are some of the people of Medina. They are firm and staunch in their hypocrisy. You, O Messenger, do not know them, but it is Allah Who knows them.